Diagnostic value of "absent" pattern in contrast-enhanced ultrasound for the differentiation of thyroid nodules

Our study sought to investigate the unique diagnostic value of "absent" pattern in contrast-enhanced ultrasound (CEUS) for the differentiation of solid thyroid nodules, also, to analyze corresponding characteristics of B-scan ultrasound (US) and real-time elastography (RTE).

A total of 96 patients enrolled in our study underwent conventional US, RTE and CEUS before fine needle aspiration (FNA) or surgery. Thyroid nodules with the same "absent" pattern of contrast-enhancement were evaluated on the basis of different ultrasound features in B-scan US and RTE. Then accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of thyroid cancer were investigated respectively.

Among the five B-scan US features, nodular border obscurity was most predictive of malignancy (accuracy 84.4%, sensitivity 75.0%, specificity 84.8%, p < 0.05). Nevertheless, none of other ultrasound features including RTE was significantly different between benign and malignant thyroid nodules (p > 0.05). Besides, both echohomogeneity and RTE had a high sensitivity of 100%.

Combined with medical history, our study allows to identify a specific role for "absent" pattern of CEUS in the differentiation of thyroid nodules with suspicious ultrasound features in conventional B-scan US and RTE.